Access control for XSLT: reading/writing files, directories and
network I/O. Access to a type of resource is granted or denied by
passing any of the following boolean keyword arguments. All of
them default to True to allow access.
read_file
write_file
create_dir
read_network
write_network
For convenience, there is also a class member DENY_ALL that
provides an XSLTAccessControl instance that is readily configured
to deny everything, and a DENY_WRITE member that denies all
write access but allows read access.
